Viscosity dependence of the kinetics of the diffusion-controlled reaction of carbon monoxide and myoglobin

This work deals with a generalization of the widely applicable theory of Hill's, later developed by Hermans. It concerns the diffusion-controlled reaction of a reagent with a polymer across an interface, in the course of which the reagent is captured by an infinitely reactive site ('sink') inside the polymer. For certain applications, it becomes necessary to introduce an alternative fate which the reagent may suffer during diffusion to the sink, namely, deactivation or decomposition. The present kinetic theory of this effect is based on the method of considering the elementary jumps responsible for diffusion, while Hill and Hermans used the complementary, continuous method based on Fick's law. The present derivation of a general rate law for the conversion of the polymer is based on a pseudo lattice model. The rate law takes the form of an infinite spectrum of first-order decay terms, and is little dependent on details of the model used or on curvature of the interface. It does depend critically on a stability constant s of the reagent, which is unity for a perfectly stable and zero for a completely unstable one. In the former case the rate law reduces substantially to that of Hill and Hermans, but covers the initial transient effect as well as the steady state. As s →0, the rate law converges uniformly to that of a first-order chemisorption of a monolayer over the appropriate range. Intermediate cases (0 < s < 1) are of interest in the chemistry of rubber latex, and probably in other fields of polymer chemistry.

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The diffusion-controlled reaction kinetics of the binding of CO and O2 to myoglobin in glycerol-water mixtures of high viscosity

Archives of Biochemistry and Biophysics ◽

10.1016/0003-9861(77)90432-5 ◽

1977 ◽

Vol 183 (1) ◽

pp. 176-188 ◽

Cited By ~ 22

Author(s):

Brian B. Hasinoff

Keyword(s):

Reaction Kinetics ◽

High Viscosity ◽

Glycerol Water ◽

Diffusion Controlled ◽

Kinetics Of ◽

Diffusion Controlled Reaction

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Thermal-Induced Transformation of Retained Austenite in the Simulated Case of a Carburized Steel

Journal of Engineering Materials and Technology ◽

10.1115/1.2902161 ◽

1993 ◽

Vol 115 (1) ◽

pp. 83-88

Author(s):

R. W. Neu ◽

Huseyin Sehitoglu

Keyword(s):

Retained Austenite ◽

Hydrostatic Stress ◽

Volume Increase ◽

Second Stage ◽

Carburized Steel ◽

Diffusion Controlled ◽

Type Relation ◽

Simulated Case ◽

Kinetics Of ◽

Diffusion Controlled Reaction

Systematic experiments were conducted on carburized 4320 steel to study thermalinduced transformation of austenite to bainite by measuring the volumetric transformation strains. Up to about 210°C, thermal-induced transformation involved a diffusion-controlled reaction and therefore was time dependent. The mechanism is similar to that described by the second stage of tempering. An Arhennius-type relation was used to model the kinetics of the reaction leading to a volume increase. A positive hydrostatic stress tended to increase the rate of transformation. The anisotropy of the transformation strains were proportional to the deviatoric stress.

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